Engine, Gearbox & Propeller Calculators
Choose a tool below. These are planning estimates. Real-world results depend on hull condition, loading, prop pitch, and sea conditions.
Boat → Engine Power Requirement
Rule-of-thumb estimate of engine power needed to reach a target speed.
Use loaded weight (fuel, water, gear, people).
Used for hull-speed indicator.
Enter values and click Calculate.
Formula: Power (HP) = (Displacement (tons)^(2/3) × Speed³) / Hull Factor
Hull factors: 45 (displacement), 70 (semi-displacement), 100 (planing).